[pbs-devel] [RFC backup 1/2] implement an api_string_type helper macro

[Dietmar Maurer]

two suggestions:

1.) Move the code to the proxmox crate

2.) Do not implement Debug (can be derived)


On 5/4/21 12:19 PM, Wolfgang Bumiller wrote:
> Signed-off-by: Wolfgang Bumiller <w.bumiller at proxmox.com>
> ---
>   src/tools.rs                 |   3 +
>   src/tools/api_string_type.rs | 105 +++++++++++++++++++++++++++++++++++
>   2 files changed, 108 insertions(+)
>   create mode 100644 src/tools/api_string_type.rs
>
> diff --git a/src/tools.rs b/src/tools.rs
> index c58569a6..98597c29 100644
> --- a/src/tools.rs
> +++ b/src/tools.rs
> @@ -18,6 +18,9 @@ use percent_encoding::{utf8_percent_encode, AsciiSet};
>   pub use proxmox::tools::fd::Fd;
>   use proxmox::tools::fs::{create_path, CreateOptions};
>   
> +#[macro_use]
> +pub mod api_string_type;
> +
>   pub mod acl;
>   pub mod apt;
>   pub mod async_io;
> diff --git a/src/tools/api_string_type.rs b/src/tools/api_string_type.rs
> new file mode 100644
> index 00000000..122fcbed
> --- /dev/null
> +++ b/src/tools/api_string_type.rs
> @@ -0,0 +1,105 @@
> +/// Helper macro to generate a simple string type wrapper.
> +///
> +/// This is meant to be used with an API-type tuple struct containing a single `String` like this:
> +///
> +/// ```ignore
> +/// api_string_type! {
> +///     #[api(format: &PROXMOX_SAFE_ID_FORMAT)]
> +///     /// ACME account name.
> +///     #[derive(Clone, Eq, PartialEq, Hash, Deserialize, Serialize)]
> +///     #[serde(transparent)]
> +///     pub struct AccountName(String);
> +/// }
> +/// ```
> +///
> +/// This will automatically implements:
> +/// * `Display` as a pass-through to `String`'s `Display`
> +/// * `Debug` as a pass-through to `String`'s `Debug`
> +/// * `Deref`
> +/// * `DerefMut`
> +/// * `AsRef<str>`
> +/// * `fn into_string(self) -> String`
> +/// * `fn as_str(&self) -> &str`
> +/// * `fn from_string(inner: String) -> Result<Self, anyhow::Error>` using
> +///   `StringSchema::check_constraints`.
> +/// * `unsafe fn from_string_unchecked(inner: String) -> Self`
> +macro_rules! api_string_type {
> +    (
> +        $(#[$doc:meta])*
> +        $vis:vis struct $name:ident(String);
> +    ) => (
> +        $(#[$doc])*
> +        $vis struct $name(String);
> +
> +        impl ::std::ops::Deref for $name {
> +            type Target = str;
> +
> +            #[inline]
> +            fn deref(&self) -> &str {
> +                &self.0
> +            }
> +        }
> +
> +        impl ::std::ops::DerefMut for $name {
> +            #[inline]
> +            fn deref_mut(&mut self) -> &mut str {
> +                &mut self.0
> +            }
> +        }
> +
> +        impl AsRef<str> for $name {
> +            #[inline]
> +            fn as_ref(&self) -> &str {
> +                self.0.as_ref()
> +            }
> +        }
> +
> +        impl $name {
> +            /// Get the contained string.
> +            pub fn into_string(self) -> String {
> +                self.0
> +            }
> +
> +            /// Get the string as slice.
> +            pub fn as_str(&self) -> &str {
> +                self.0.as_str()
> +            }
> +
> +            /// Create an instance directly from a `String`.
> +            ///
> +            /// # Safety
> +            ///
> +            /// It is the caller's job to have validated the contents.
> +            /// While there are no memory safety issues, a wrong string can cause API calls to
> +            /// fail parameter validation.
> +            pub unsafe fn from_string_unchecked(name: String) -> Self {
> +                Self(name)
> +            }
> +
> +            /// Create an instance directly from a `String`, validating it using the API schema's
> +            /// [`check_constraints`](::proxmox::api::schema::StringSchema::check_constraints())
> +            /// method.
> +            pub fn from_string(inner: String) -> Result<Self, ::anyhow::Error> {
> +                match &Self::API_SCHEMA {
> +                    ::proxmox::api::schema::Schema::String(s) => s.check_constraints(&inner)?,
> +                    _ => unreachable!(),
> +                }
> +                Ok(Self(inner))
> +            }
> +        }
> +
> +        impl ::std::fmt::Debug for $name {
> +            #[inline]
> +            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
> +                ::std::fmt::Debug::fmt(&self.0, f)
> +            }
> +        }
> +
> +        impl ::std::fmt::Display for $name {
> +            #[inline]
> +            fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
> +                ::std::fmt::Display::fmt(&self.0, f)
> +            }
> +        }
> +    );
> +}